The present disclosure relates to a semiconductor device of a common source structure and a manufacturing method of a semiconductor device of the common source structure.
Since a recessed common source (RCS) process in a process of manufacturing a semiconductor device such as a flash memory has advantages of a simple structure, operational excellence, etc., the RCS process attracts large public attention. However, since the RCS process is complicated in process and short in process margin, the RCS process has a problem in that production yield is deteriorated.
FIG. 1 is a perspective view showing a form of a semiconductor device of a common source structure and FIGS. 2 to 4 are cross-sectional views showing a process of forming a common source taken along line A-A′ of FIG. 1.
Referring to FIG. 1, a gate 10 serving as a word line is formed on a semiconductor substrate 40 and a common source 20 having a line form is formed along one side of the gate 10.
A drain (not shown) is formed at the other side of the gate 10 and a device separator 30 is formed vertical to the line of the gate 10.
The device separator 30 partitions a memory cell area. The common source 20 has a trench-type structure with the device separator 30.
Referring to FIG. 2, a second device separator 21 for forming the common source is formed on the semiconductor substrate 40 along a line of the gate 10. In an effort to lend greater clarity, the device separator 30 is not shown in FIGS. 2-4.
As shown in FIG. 3, the trench of the second device separator 21 is exposed by removing the oxide layer that forms the second device separator 21 by performing an etching process, and as shown in FIG. 4, after a photoresist pattern (not shown) is formed exposing one side of the line of the gate 10 and the trench T at the one side of the line of the gate 10, the common source 20 having the line form is completed by injecting ions into the exposed one side of the line of the gate 10.
At this time, as shown in FIG. 4, photoresist remnants may remain in the trench, blocking the ions from reaching into the substrate, thereby causing the common source 20 to be opened (i.e. fail to provide a continuous path for charge).
Further, during the etching of the oxide layer of the second device separator 21, the surface of the semiconductor substrate 40 is damaged, such that a profile of a drain area at the other side of the gate 10 is deteriorated to thereby influence the flow of current.